Hot top



Aug. 4, 1936. E. TURNER ET AL HOT To? Filed April 3, 1934 1 7 I 4 il I 2z I (/7 v I 1/ v I 11/ IIII LIL Patented Aug. 4, i936 UNHTED STATESPATENT HOT TOP Delaware Application April 3, 1934, Serial No. 718,796

2 Claims.

. This invention relates to a hot top such as frequently is used inconnection with ingot molds for confining a molten mass of metal at theupper end of the ingot mold available for feeding into 5 voids or thelike created in the course of the solidification of the ingot. Theinvention provides a. remedy for the difliculty sometimes encounteredwith bridging of congealed metal across the juncture of the hot topcavity and mold cavity.

A subsidiary feature of my invention is an improvement in the method ofproducing refractory articles formed with an extremity which does notaiford a stable base; and one object of my invention is to provide animproved procedure for producing such articles in accordance with whichthe articles may be piled in a kiln by the use of integral pads, thearticles fired, andthe pads then broken ofi.

In general, the usefulness of a hot top depends upon its ability tomaintain in the molten state a reservoir of metal at the upper end of aningot mold and to feed molten metal downwardly into the cavities, voidsor the like which would otherwise result from the solidification of theingot.

The hot top is customarily made of material which has high insulatingvalue; and heat flows outwardly and is dissipated from the ingot mold ata considerably greater rate than takes place through the confining wallsof refractory matefor the heat of the metal within the lower portion ofthe hot top by passing around the lower edge of the hot top; andtherefore, there is a tendency for the metal in the lower portion of 35the hot top to congeal, thus forming a bridge,

' while there is a substantial body of molten metal within the hot topabove this bridge. It will be apparent, therefore, that it is desirableto prevent such a bridge forming; as the bridge cuts 40 ofi theefiectiveness of the hot top at the point in the solidification of theingot at which such bridge forms.

In accordance with my invention, I prevent such a bridge forming at thelower end of the 45 hot top by increasing the transverse dimension ofthe cavity toward the lower end of the hot top; thus making it lesslikely that the bridge will form, due to the increased size of the spaceacross which the bridge must extend.

50 This improvement may be embodied in a number of forms, as hot tops ofa variety of shapes and constructions are commonly used in the pouringof ingots. Two illustrative embodiments are shown in the drawing, in oneof which the g walls of refractory material of the hot top are rial ofthe hot top. There is an avenue of escape solid and are tapered to awedge-shaped extremity which would interfere with production of such anarticle in the customary manner. To overcome this difiiculty, bearingpads are formed integrally with the tapered extremity of the article;and 5 when the articles are piled in the kiln, these bearing padsafi'ord a support permitting the articles to be superimposed. When thearticles are hard. ened by firing, the pads may be broken off leavingthe desired tapered edge. 10

In the drawing which illustrates my invention,

Fig. 1 is a plan view of a hot tophaving compound walls;

Fig. 2 is a sectional view on line II--II of Fig. 1, showing how myinvention may be embodied in 15 this type of hot top;

Fig. 3 is a plan view corresponding to Fig. 1 of another type of hot topin which the walls of refractory material are solid;

Fig. 4 is a bottom plan view of a hot top such 20 as shown in Fig. 3with pads formed integrally with the lower extremity;

Fig. 5 is a sectional view on the line V-V of Fig. 4, a second hot topbeing superimposed to illustrate how these articles may be piled in a 25kiln due to the provision of the supporting pads; and

Fig. 6 is a sectional view on the line VI-VI of Fig. 3 illustrating ahot top from which the pads have been broken oiT.

The hot top shown in Figs. 1 and 2 is a modification of a well knowntype of hot top which has marked elnciency in insulating the mass ofmolten metal confined at the upper end of the ingot mold. The compoundwall of refractory material which surrounds the space for confining themolten mass of metal is made up of an inner shell '6 and an outer shell8 tied by ribs or webs 9. Vertical air spaces ll extend through thewalls and greatly increase the insulating efiect of the 40 hot top. RibsI2 formed integrally with the refractory wall of the hot top may beengaged by blocks it for supporting the hot top so as to project withinthe upper end of the ingot mold i5.

While hot tops of this type are frequently chamfered around the internallower edge, such chamfering raises but'slightly the throat or level atwhich the minimum cross-section of the hot top cavity begins. Freezingwithin the throat has been a troublesome problem where the hot top iscalled upon to feed a large proportion of its supply of molten metaldownwardly into the solidifying ingot. This difliculty has been overcomeby substantially lifting the throat upwardly within the hot top. Asillustrated in Fig. 2, the hot top is made of'such configuration thatthe space for confining the molten mass of metal is of substantiallyuniform cross-section down as far as the throat H, the lower portion ofthe space being enlarged due to the receding walls which surround thisportion of the hot top cavity. By thus enlarging the lower portion ofthe hot top cavity, and preferably by gradually increasing thetransverse dimension of this space toward the lower extremity of the hottop, the throat I1 is substantially lifted within the hot top andfreezing within the throat so as to cut off the supply of molten metalby formation of a bridge is delayed until substantially all of theavailable molten metal confined within the hot top has performed itspurpose.

Preferably the throat should be lifted about one-third of the height ofthe hot top, although improved results over the ordinary hot top are.obtained by elevating the throat to a somewhat smaller extent. Whilethe throat may be lifted somewhat more than a third of the height of thehot top, obviously the result of thinning out the walls for a majorportion of the height is merely to decrease the insulating value ofthese walls.

In the type of hot top shown in Figures 3 to 6. inclusive, therefractory walls 20 of the hot top are solid. Ribs or lugs H are formedintegrally with the walls 20 for positioning the hot top on the mold insimilar fashion as illustrated in Figure 2. In order to increase thetransverse dimension of the hot top cavity toward the lower extremity ofthe hot top, the refractory material in the lower portion of the wallsill is tapered, as illustrated at 23 in Figures 5 and 6. Preferably, thetaper is a. gradual taper so as to gradually enlarge the cross-sectionof the space within the walls 20. Similarly as pointed out in connectionwith the first embodiment, it is preferable to raise the throat 24 aboutone-third of the height of the hot top, although variations one way orthe other are allowable, as above pointed out.

As the tapered extremity 23 of the hot top does not afiord a suitablerest when superimposing hot tops, it would be difficult to produce thesehot.

tops in accordance with the usual kiln practice. This difiiculty hasbeen met by so forming the refractory material as to provide supportingor hearing pads 25 which are integral with the tapered extremity 23. Asillustrated in broken lines in Figure 5, the hot tops may be piled in akiln by virtue of the integral pads 25, which provide stable support forthe superimposed articles. A sumcient number of the integral pads 25will be 5 spaced about the extremity of the hot top to beat the weightof the superimposed articles. As indicated by Figure 5, the hot tops arepreferably fired with the tapered extremity uppermost, the hot top nextabove resting on the bearing pads 25. The hot tops are then fired in thecustomary manner in a suitable heating chamber, such as the kilnreferred to; and after the removal of the hot tops from the kiln, thepads 25 are broken oif. If desired, the refractory material when moldedmay be scored at the junction of the pad 25 and tapered extremity 23, asshown at 26, to facilitate the breaking off of the pads 25. As indicatedat 25a, in Figure 6, the tapered extremity 23 is left with an internalsurface which is sub- 15 stantially conical.

In both embodiments of the invention, the refractory walls surroundingthe lower portion of the hot top cavity recede, thus substantiallylifting the throat upwardly within the hot top. Pursuant to this changein the level at which the minimum cross-section of the hot top cavitybegins, the likelihood of congealed metal bridging across the throat islargely eliminated. This is of particular importance where the availablesupply of molten metal is not substantially larger than the requirementsof the ingot mold. In other words, if the capacity of the hot top hasbeen carefully calculated so as not to entail an excessive amount ofmetal in the head, which must be discarded, the substantial lifting ofthe throat within the hot top is of marked advantage in making availablea sufiicient quantity of molten metal for feeding the pipe or likecavity which would otherwise occur in the ingot.

While we have illustrated and described certain preferred embodiments ofour invention, it will be understood that the invention may be otherwiseembodied and practiced within the scope of the following claims.

We claim:

1. as an article of manufacture, a hot top having a feeder spacesurrounded by refractory material tapered from the lower extremityupward 1y for at least a portion of the height of said feeder space withthe exception of supporting pads formed integrally with said taperedportion.

2. As an article of manufacture, a hot top having walls of refractorymaterial having the lower portion tapered to a wedge-shaped lowerextremity with spaced bearing pads formed integrally with said taperedportion.

ERNEST J. TURNER.

WILLIAM A. TURNER.

